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1. Description of Related Art
Not Applicable
2. Field of the Invention
The present invention relates to call setup and call control in a wireless communication system. More particularly, the present invention relates to a method and apparatus for providing call setup and call control in congested wireless cells.
Presently, when a mobile call setup is being attempted and congestion is encountered within a calling or a called cell, a number of options are available to call setup related network elements within the wireless communication system including, for example, directed re-try. Directed re-try involves a Mobile Switching Center (MSC) attempting to direct call setup from the original, congested cell to a neighboring cell, or the like, which is not congested and which is capable of providing alternate service to a called or calling mobile station (MS). Another option, in the case of calling cell congestion, is to queue the calling MS""s request to the MSC for a traffic channel until channel resource availability improves. The queuing process involves the calling MS remaining on the call until a traffic channel is available, which is preferably a small duration of time. It should be noted that the duration for which the call can be in a queue waiting for a traffic channel is limited as other key resources are seized. It should further be noted that subscriber services may exist relating to call completion (e.g. call completion on busy or call completion on no reply). These call completion services are based on the status of the called subscriber, and not based on cell congestion.
Several problems and undesirable consequences arise in relation to cell congestion, which may occur on either the originating or terminating side of a call, when attempting to seize a traffic channel within a cell. In some situations, the consequences may be as simple as the calling party re-attempting the call at a later time. Congestion may of course be reencountered at the later time also. In some cases the calling party may not make a reattempt at a later time or make subsequent re-attempts if the initial re-attempt was unsuccessful. For a wireless communication system operator or service provider, an ultimate failure to re-attempt a call means a loss of revenue.
In addition, undesirable consequences may arise related to the calling party being frustrated by inability to complete the call based on the congested status of the network and further, has no means of knowing when the congested status of the network has changed.
Thus, it can be seen that while the above mentioned methods such as queueing and directed re-try address certain issues and problems, the difficulty posed by, for example, the inability of either the calling or called parties to know if a network is no longer congested remains unaddressed.
It would be appreciated therefore in the art for a system which would provide, for example, the calling party a way to be in a position to make a previously failed call once cell congestion has disappeared.
It would further be desirable for the called party to receive calls that could not be received due to congestion.
It would still further be desirable for the operator or service provider to maximize the system capacity by increasing overall call throughput particularly during intervals associated with traffic peaks by minimizing the impact of congestion during traffic peaks.
To reduce the impact of cell congestion, a method and apparatus for providing a call completion service in at least one service area associated with a wireless communication system are described. The call completion service may be provided for completing a call attempt originated between a calling party and a called party at either end of the call. It should be noted that in accordance with various embodiments of the present invention, the call completion service may be provided to a calling party when the calling party is a mobile station originating a call, when congestion is encountered in the cell or cells which are providing service to the calling party. The call completion service may further be provided to either a calling party or called party when the called party is a mobile station intended to terminate a call, when cell congestion is encountered in the cell or cells providing service to the called party. It should further be noted that the calling party in a case of congestion encountered in the called party""s cell may be a mobile station, a PSTN subscriber or any originating calling type. Thus a call completion service in accordance with the present invention may be provided as described above for calls placed from a mobile station (MS) to another MS within the same or different service areas, from a PSTN subscriber or any originating station type, to a MS, or from a MS to a PSTN subscriber or any terminating station type.
In accordance with one embodiment of the present invention, it may be determined that congestion has occurred in at least one cell associated with the call attempt whereupon information related to the call attempt may be stored, for example, in a storage register, such as a Visitor Location Register (VLR), associated with an MSC in the one or more coverage areas where the cell congestion was encountered. Information related to the call attempt may be monitored including one or more of: position information associated with the called and calling parties and information associated with the at least one cell to determine if congestion is still present. If the one or more of the called and calling parties is still within the coverage area associated with the at least one cell, based on, for example, any one of the following: registration of the one or more of the calling and the called parties in a new respective cell, call-related activity associated with the one or more of the calling and the called parties in the new respective cell, messaging activity associated with the one or more of the calling and the called parties in the new respective cell, unanswered paging messages associated with the one or more of the calling and the called parties in the respective cell, answered paging messages associated with the one or more of the calling and the called parties in the new respective cell, control channel activity associated with the one or more of the calling and the called parties in the new respective cell, or mobile positioning information associated with the one or more of the one or more calling and the called parties indicating that the one or more of the calling and the called parties is within the coverage area associated with the new respective cell position information, then a call may be set up between the calling party and the called party when it is determined that congestion is no longer present. It should be noted that a level of congestion may be determined, for example, by the presence of an available traffic channel in the cell. Alternatively, a congestion level may be determined based on the availability of a predetermined number of traffic channels. By selecting the predetermined number according to, for example, usage information associated with the cell, which usage information may be incorporated into, for example, channel utilization calculations, or the like, as may be known in the art, further congestion in the cell may be prevented. If it is determined that the party that encountered congestion is not within the coverage area of the congested cell and it is further determined that the party is within the coverage area of at least one new cell and it is still further determined that congestion is not present in the new cell, then a call may be set up between the calling party and the called party.
In accordance with another embodiment of the present invention, the calling party may be contacted when it is determined that congestion is no longer present to request confirmation that the call associated with the call attempt should be set up. Thereafter, upon confirmation by the calling party the call may be set up.
In still another embodiment of the present invention, a call completion service may be provided for completing an established call between a calling party and a called party where cell congestion is encountered resulting in a failed handoff attempt. Accordingly, a failed handoff attempt to a new cell may be detected during the established call whereupon it may be determined that congestion has occurred in the new cell and/or in the present cell. If congestion is present in the new cell resulting in the call being dropped, information related to the failed handoff attempt may be stored and information related to the failed handoff attempt may be monitored including: position information associated with the called and calling parties and information associated with the existing and new cell to determine a congestion level and to determine if the parties are still within the coverage area. A congestion level may be determined in one or more new respective cells and a call may be set up between the calling party and the called party responsive to the determined congestion level in one of the or more new respective cells. Congestion levels may be determined for example based on whether a traffic channel becomes available or whether a predetermined number of traffic channels become available.